Radio terminal device, transmission directivity control method, and transmission directivity control program

Abstract

An adaptive array terminal ( 2000 ) includes a reception adaptive array unit ( 2030 ) extracting a reception signal from a base station by multiplying signals from respective antennas (#AN 1 –#AN 2 ) of an array antenna by respective reception weights, a transmission adaptive array unit ( 2090 ) applying to respective antennas of the array antenna a plurality of signals generated by multiplying by a transmission signal by transmission weights to form transmission directivity, and a transmission weight calculator ( 2070 ) calculating transmission weights added with a specified constraint in accordance with designation in a reception signal.

The invention claimed is: 
     
       1. A radio terminal apparatus comprising:
 an array antenna including a plurality of antennas (#ANT  1 , #ANT  2 ), 
 a reception signal processing unit extracting a reception signal from a base station by multiplying signals from respective said antennas of said array antenna by respective reception weights, 
 a transmission signal processing unit applying to respective said antennas of said array antenna a plurality of signals generated by multiplying a transmission signal by transmission weights to form transmission directivity, and 
 transmission weight generation means for adaptively switching between a mode of calculating transmission weights forming transmission directivity towards said base station and a mode of calculating said transmission weights added with a specified constraint, in accordance with designation in said reception signal, to generate said transmission weights. 
 
     
     
       2. The radio terminal apparatus according to  claim 1 , wherein said transmission weight generation means provides, when said reception signal processing unit multiplies a signal from said base station by reception weights having reception directivity, said reception weights as said transmission weights to said transmission signal processing unit, in accordance with designation from said base station. 
     
     
       3. The radio terminal apparatus according to  claim 1 , wherein said transmission weight generation means generates, when said reception signal processing unit multiplies a signal from said base station by reception weights having reception directivity, said transmission weights based on a transmission response vector estimated from a reception response vector, in accordance with designation from said base station. 
     
     
       4. The radio terminal apparatus according to  claim 1 , wherein said transmission weight generation means sets said transmission weight with a fixed amplitude and phase when said reception signal processing unit multiplies a signal from said base station by reception weights having reception directivity, in accordance with designation from said base station. 
     
     
       5. The radio terminal apparatus according to  claim 1 , wherein said transmission weight generation means carries out a process of setting a fixed value of amplitude of said transmission weight, and gradually shifting a phase of said transmission weight according to a predetermined sequence when said reception signal processing unit multiplies a signal from said base station by reception weights having reception directivity, in accordance with designation from said base station. 
     
     
       6. The radio terminal apparatus according to  claim 5 , wherein
 a signal transferred between said base station and said radio terminal apparatus is divided into a plurality of frames, 
 said transmission weight generation means calculates said phase of said transmission weight by a weighted mean of said reception weights in past and current frames. 
 
     
     
       7. The radio terminal apparatus according to  claim 1 , wherein
 a signal transferred between said base station and said radio terminal apparatus is divided into a plurality of frames, 
 said transmission weight generation means calculates said transmission weight based on a weighted mean of reception response vectors in past and current frames when said reception signal processing unit multiplies a signal from said base station by reception weights having reception directivity, in accordance with designation from said base station. 
 
     
     
       8. The radio terminal apparatus according to  claim 1 , further comprising reception level detection means for detecting a reception level of each of said antennas,
 wherein said transmission weight generation means generates said transmission weights so as to select an antenna of the highest reception level. 
 
     
     
       9. The radio terminal apparatus according to  claim 1 , wherein
 a signal transferred between said base station and said radio terminal apparatus is divided into a plurality of frames, 
 said transmission weight generation means takes a weighted mean of transmission weights calculated in past and current frames newly as a transmission weight of the current frame when said reception signal processing unit multiplies a signal from said base station by a reception weight having reception directivity, in accordance with designation from said base station. 
 
     
     
       10. The radio terminal apparatus according to  claim 1 , further comprising storage means for storing in advance a set of transmission weights that increases orthogonality of reception response vectors at said base station,
 wherein said transmission weight generation means selects and provides to said transmission signal processing unit said transmission weight stored in said storage means, in accordance with designation from said base station. 
 
     
     
       11. A transmission directivity control method of a radio terminal apparatus including an array antenna having a plurality of antennas (#ANT  1 , #ANT  2 ) and for separating and extracting a reception signal from a base station by multiplying signals from respective said antennas of said array antenna by respective reception weights, said method comprising the steps of:
 adaptively switching between a mode of calculating transmission weights forming transmission directivity towards said base station and a mode of calculating said transmission weights added with a specified constraint, in accordance with designation in said reception signal, to generate said transmission weights, and 
 providing to respective said antennas of said array antenna a plurality of signals generated by multiplying a transmission signal by said transmission weights to form said transmission directivity. 
 
     
     
       12. The transmission directivity control method according to  claim 11 , wherein said step of generating transmission weights includes the step of, when a signal from said base station is multiplied by reception weights having reception directivity, taking said reception weights as said transmission weights, in accordance with designation from said base station. 
     
     
       13. The transmission directivity control method according to  claim 11 , wherein said step of generating transmission weights includes the step of generating, when a signal from said base station is multiplied by reception weights having reception directivity, said transmission weights based on a transmission response vector estimated from a reception response vector, in accordance with designation from said base station. 
     
     
       14. The transmission directivity control method according to  claim 11 , wherein said step of generating transmission weights includes the step of setting said transmission weight with a fixed amplitude and phase when a signal from said base station is multiplied by reception weights having reception directivity, in accordance with designation from said base station. 
     
     
       15. The transmission directivity control method according to  claim 11 , wherein said step of generating transmission weights includes the step of, when said reception signal processing unit multiplies a signal from said base station by reception weights having reception directivity, carrying out a process of setting a fixed value of amplitude of said transmission weight, and gradually shifting a phase of said transmission weight according to a predetermined sequence, in accordance with designation from said base station. 
     
     
       16. The transmission directivity control method according to  claim 11 , wherein
 a signal transferred between said base station and said radio terminal apparatus is divided into a plurality of frames, 
 said step of generating transmission weights includes the step of calculating a phase of said transmission weight based on a weighed mean of said reception weights in past and current frames. 
 
     
     
       17. The transmission directivity control method according to  claim 11 , wherein
 a signal transferred between said base station and said radio terminal apparatus is divided into a plurality of frames, 
 said step of generating transmission weights includes the step of calculating said transmission weight based on a weighted mean of reception response vectors in past and current frames when a signal from said base station is multiplied by reception weights having reception directivity, in accordance with designation from said base station. 
 
     
     
       18. The transmission directivity control method according to  claim 11 , further comprising the step of detecting a reception level of each of said antennas,
 wherein said step of generating transmission weights includes the step of generating said transmission weights so as to select an antenna of highest reception level. 
 
     
     
       19. The transmission directivity control method according to  claim 11 , wherein
 a signal transferred between said base station and said radio terminal apparatus is divided into a plurality of frames, 
 said step of generating transmission weights includes the step of taking a weighted mean of transmission weights calculated in past and current frames newly as a transmission weight of the current frame when a signal from said base station is multiplied by reception weights having reception directivity, in accordance with designation from said base station. 
 
     
     
       20. The transmission directivity control method according to  claim 11 , further comprising the step of storing in advance a set of transmission weights that increases orthogonality of reception response vectors at said base station,
 wherein said step of generating transmission weights includes the step of selecting said transmission weight stored in advance in accordance with designation from said base station. 
 
     
     
       21. A transmission directivity control program of a radio terminal apparatus including an array antenna having a plurality of antennas (#ANT  1 , #ANT  2 ) and for separating and extracting a reception signal from a base station by multiplying signals from respective said antennas of said array antenna by respective reception weights, said program causing a computer to execute the steps of:
 adaptively switching between a mode of calculating transmission weights forming transmission directivity towards said base station and a mode of calculating said transmission weights added with a specified constraint, in accordance with designation in said reception signal, to generate said transmission weights, and 
 providing to respective said antennas of said array antenna a plurality of signals generated by multiplying a transmission signal by said transmission weights to form said transmission directivity. 
 
     
     
       22. The transmission directivity control program according to  claim 21 , wherein said step of generating transmission weights includes the step of, when a signal from said base station is multiplied by reception weights having reception directivity, taking said reception weights as said transmission weights, in accordance with designation from said base station. 
     
     
       23. The transmission directivity control program according to  claim 21 , wherein said step of generating transmission weights includes the step of generating, when a signal from said base station is multiplied by reception weights having reception directivity, said transmission weights based on a transmission response vector estimated from a reception response vector, in accordance with designation from said base station. 
     
     
       24. The transmission directivity control program according to  claim 21 , wherein said step of generating transmission weights includes the step of setting said transmission weight with a fixed amplitude and phase when a signal from said base station is multiplied by reception weights having reception directivity, in accordance with designation from said base station. 
     
     
       25. The transmission directivity control program according to  claim 21 , wherein said step of generating transmission weights includes the step of, when said reception signal processing unit multiplies a signal from said base station by reception weights having reception directivity, carrying out a process of setting a fixed value of amplitude of said transmission weight, and gradually shifting a phase of said transmission weight according to a predetermined sequence, in accordance with designation from said base station. 
     
     
       26. The transmission directivity control program according to  claim 21 , wherein
 a signal transferred between said base station and said radio terminal apparatus is divided into a plurality of frames, 
 said step of generating transmission weights includes the step of calculating said phase of said transmission weight based on a weighed mean of said reception weights in past and current frames. 
 
     
     
       27. The transmission directivity control program according to  claim 21 , wherein
 a signal transferred between said base station and said radio terminal apparatus is divided into a plurality of frames, 
 said step of generating transmission weights includes the step of calculating said transmission weight based on a weighted mean of reception response vectors in past and current frames, when a signal from said base station is multiplied by reception weights having reception directivity, in accordance with designation from said base station. 
 
     
     
       28. The transmission directivity control program according to  claim 21 , further comprising the step of detecting a reception level of each of said antennas,
 wherein said step of generating transmission weights includes the step of generating said transmission weights so as to select an antenna of highest reception level. 
 
     
     
       29. The transmission directivity control program according to  claim 21 , wherein
 a signal transferred between said base station and said radio terminal apparatus is divided into a plurality of frames, 
 said step of generating transmission weights includes the step of taking a weighted mean of transmission weights calculated in past and current frames newly as a transmission weight of the current frame when a signal from said base station is multiplied by reception weights having reception directivity, in accordance with designation from said base station. 
 
     
     
       30. The transmission directivity control program according to  claim 21 , further comprising the step of storing in advance a set of transmission weights that increases orthogonality of reception response vectors at said base station,
 wherein said step of generating transmission weights includes the step of selecting said transmission weight stored in advance in accordance with designation from said base station.